This invention relates to a two cycle engine lubricating system and more particularly to an improved lubricating system for reciprocating machines.
As is well known, two cycle combustion internal engines are normally lubricated by supplying minute quantities of lubricant to the engine through its induction and porting system for lubricating the various moving components of the engine. This type of lubricating system has the advantage of extreme simplicity. However, it is extremely important that the amount of lubricant supplied to the engine be accurately controlled so as to insure adequate lubrication without excess lubricant being contain in the exhaust gases of the engine.
The lubricant for two cycle engines is supplied in a wide variety of manners. For example, lubricant may be mixed with the fuel which is consumed by the engine, lubricant may be sprayed into the induction system of the engine, and/or lubricant may be delivered directly to certain components of the engine for their lubrication. Obviously, combinations of the above system may be employed. Regardless of how the lubricant is supplied, however, it is desirable to ensure that lubricant can not collect in any portion of the engine due to condensation. If this occurs, the condensed lubricant can periodically flow into the engine along with the fuel and cause irregular combustion or other problems.
It has been proposed, therefor, to provide some arrangement which will insure that lubricant can not collect in lower portions of the engine. For example, systems have been proposed for providing a drain passage that extends from the lower portion of the crankcase chamber back to the induction system so that the air flowing to the engine through the induction system will draw the condensed lubricant and/or fuel back into the induction system for redistribution.
The previously proposed systems have, however, provided a number of difficulties. For example, in outboard motor applications the engine is normally positioned with its crankshaft rotating about a vertically extending axis and the cylinder bores extending horizontally. As is typical with two cycle engines, each crankcase chamber is sealed from the other. However, these seals inherently permit some leakage from the upper most cylinders to the lowermost cylinders. When this occurs, even if conventional type of recirculating or drain systems are employed, the lowermost cylinders will tend to receive more fuel and lubricant than the uppermost cylinders. This can cause inadequate lubrication and, furthermore, can cause excess of smoke in the exhaust and poor running.
It is, therefor, a principle object of this invention to provide an improved lubricating system for a two cycle engine.
It is a further object of this invention to provide an improved lubricating system for a two cycle engine wherein the engine is disposed with its cylinders horizontally oriented.
It is a further object of this invention to provide an improved lubricating system for a horizontally disposed two cycle multiple cylinder engine that will balance the lubrication for the individual cylinders.
Various arrangements have been provided in horizontally disposed engines so as to introduce lubricant to the area of the cylinder bore that is swept by the piston for lubricating the sliding surfaces. Generally, however, this is done by introducing the lubricant at a low area in the cylinder. As a result, the lubricant does not have an opportunity to flow completely around the cylinder bore and only the lowermost portion receives adequate lubrication,
It is, therefor, a still further object of this invention to provide an improved lubricating structure for the cylinders and pistons of a horizontally disposed engine.
It is a further object of this invention to provide an improved lubricating system that will insure that substantially the entire cylinder bore circumference and piston circumference are lubricated.
Although the use passages in the cylinder itself for introducing lubricant to the cylinder bore are advantageous, this requires casting or machining techniques which may be difficult, particularly with multiple cylinder engines.
It is, therefor, a still further object of this invention to provide an improved cylinder bore lubricating structure wherein the lubricant is delivered to the cylinder bore through the piston rather than through the cylinder.